The invention relates to a component interacting with electromagnetic radiation, and a method of manufacturing such a component. The arrangement according to the invention relates particularly to organic semiconductor devices emitting and detecting optical radiation.
Light Emitting Diode (LED) structures consisting of organic, light-emitting micro-pixels and utilizing a sol-gel glass material can be used to manufacture light, effective devices and components which operate at a low voltage and employ different optical wavelengths. Organic electroluminescent components are typically based on the laminated structure of semiconductor films, situated between two electrodes. As it is well known, such films can be manufactured of various semiconducting organic materials, which can be made to emit electromagnetic radiation. Semiconducting organic materials which can be used in the manufacture of Organic Light-Emitting Devices (OLED) include polymers and molecules where the structure of molecular orbitals enables excitation of electrons to a higher excited state, which is thereafter discharged in the form of electromagnetic radiation.
Semiconducting organic materials include several compounds containing aromatic groups, and complexes thereof with inorganic ions, for example tris-(8-hydroxyquinolinato)aluminum (Alq3), tris-(8-hydroxyquinolinato)europium (Euq3), tris-(8-hydroxyquinolinato)gallium (Gaq3), N,Nxe2x80x2-diphenyl-N,Nxe2x80x2-bis-(3-methylphenyl)-1,1xe2x80x2-biphenyl-4,4xe2x80x2-diamine (TPD), 5,6,11,12-tetraphenylene-naphthacene (rubrene), 1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene (PPCP), 2-(biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD), tris(p-totyl)amone (TTA), and the like.
Polymers that are suitable in the manufacture of OLEDs include poly(phenylenevinylene) (PPV) and derivatives thereof, such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV), poly(3-alkylthiophene) (P3AT), polyvinylcarbazole (PVK), poly(cyanphthalylidene) (PCP), poly[p-phenylene-2,6-benzobis(oxazole)] (PBO), poly[(1-dodecyloxy-4-methyl-1,3-phenylene-(2,5xe2x80x3-terthienylene)] (mPTTh), polyacetylene (PA), polyaniline (PANI), polythiophene (PT), polypyrrole (Ppy), and the like.
Generally used optoelectronically active semiconductor molecules are TPD and Alq3, and the junction between the molecules operates as a LED based on electroluminescence. A prior art pixel LED is prepared by first forming, from a sol-gel glass, positions for the pixels for example on an electrode situated on a glass substrate, such as indium tin oxide (ITO), in such a way that the electrode is covered with the sol-gel glass in a gas or liquid phase. The sol-gel glass is thereafter stabilized and/or hardened into its final form so that the glass covers the entire electrode except for the pixels. In empty recesses provided at the pixels and surrounded by the sol-gel glass, the recesses having typically a depth of micrometers, are formed junctions of semiconducting materials, such as a junction between TPD and Alq3. A second electrode is thereafter grown, typically in a gas phase, over the entire surface or at least at the pixels comprising a semiconductor junction, the electrode being also supported with a substrate, if required. Such a component is set forth, for example, in Organic light emitting micro-pixels on hybrid sol-gel glass arrays, by Rantala et al (Proceedings of Finnish Optics Days, p 42, 1998, ISBN 951-42-4944-5), which is incorporated herein by reference. When a controlling bias voltage is applied to the electrodes, electrons are injected from the first electrode, which preferably has a low work function, and holes are injected from the second electrode, which preferably has a high work function. When the electrons and the holes recombine, the organic semiconductor used as the luminescent material is transferred to an excited state, which emits electromagnetic radiation when it is discharged. The LED thus emits at a wavelength determined by the used organic semiconducting materials, such as TPD and Alq3 molecules, the wavelength usually being in the optical band of electromagnetic radiation, i.e. ultravioletxe2x80x94visible lightxe2x80x94infrared.
A problem with the prior art arrangement is the weak stability of the components, which results from, for example, weak adhesion of the electrode materials. Another problem is the complicated manufacturing process.
A purpose of the invention is to provide a component and a manufacturing method avoiding the problems mentioned above. This is achieved with an optoelectronic component comprising at least one pixel comprising a first and a second electrode for electric coupling, and between the electrodes an optoelectronically active material. In the component according to the invention, the optoelectronically active material is a hybrid sol-gel to which is chemically attached a material affecting the optoelectronic properties and a radiation sensitive polymer material, and the optoelectronically active material is hardened and patterned using at least one of the following: UV radiation, X-rays, electron radiation and chemical treatment.
The problems can also be solved with a method of manufacturing an optoelectronic component, the method utilizing at least a first and a second electrode and between them an optoelectronically active material. The manufacturing method according to the invention comprises preparing the optoelectronically active material by chemically supplementing the sol-gel with a material affecting the optoelectronic properties and a radiation sensitive polymer material, the sol-gel being thus changed to hybrid sol-gel; spreading the optoelectronically active hybrid sol-gel on the first electrode; hardening the hybrid sol-gel by using at least one of the following: UV radiation, X-rays, electron radiation and chemical treatment; forming the second electrode on the optoelectronically active hybrid sol-gel.
The component and the manufacturing method according to the invention provide several advantages. The process is simple since it is based only on a known manufacturing technique that is economical and easy to control. For example, oxides are always formed on the surface of metals and they constitute a strong bond in the sol-gel material. Therefore the component is stable and durable.